New technology that fuses magnetic resonance imaging (MRI) and ultrasound is improving the detection of prostate cancer and helping to avoid unnecessary biopsies. Bryant Poole, MD, of Urology Centers of Alabama, says the technology has been available for about four years but has become more widespread over the past six months.
Urology Centers of Alabama is now using the UroNav® system to do MRI/ultrasound fusion biopsies of the prostate. “In the past, we were doing 12-template biopsies, six on each side, and they were just random biopsies,” Poole says. “Studies have shown that some significant cancers have been missed by doing it that way, and our cancer detection rate using the 12-template biopsy is about 32 percent. The MRI/ultrasound fusion will allow us to identify these cancers more specifically, and we will be better able to determine who needs to be treated and who doesn’t.”
Poole says that the overall cancer detection rate with the MRI/ultrasound fusion biopsy is 54 percent. “But if you stratify that for the lesions that are highly suspicious, then it’s 80 percent so this technology increases the sensitivity and the specificity. Not only is this technique more accurate, we think we can reliably detect the cancers that look more aggressive on the MRI as well.”
The first step in the biopsy process is to send the patient for a multi-parametric MRI. “They use three different parameters, a T2 weighted image, diffusion-weighted imaging, and dynamic contrast enhancement. They use the three parameters of the MRI to calculate a score of one to five to assess how worried they are about a lesion that might be cancer. We do biopsies on the ones that are three or higher,” Poole says. “The radiologist uses the MRI to identify the lesion, marks a circle around it, and that becomes our target.”
In a follow-up appointment, the patient will return to the doctor’s office for a real-time, three-dimensional ultrasound, and the MRI is fused with the ultrasound image. “While we do the ultrasound, we can see the target that was marked on the MRI so we know where to direct our needle,” Poole says.
With the more specific readings from the MRI/ultrasound fusion, physicians also are more able to determine when cancer is not a threat. “There are two problems with doing the 12-template biopsy,” Poole says. “One is that we may not be catching the significant lesions or significant cancers that need to be treated, and the other problem is that we may be catching too many cancers that don’t need to be treated. I think the MRI will allow us to stratify who needs to be treated and who doesn’t.
“If you do the MRI and you don’t identify anything that looks suspicious, that patient may not need a biopsy at all. As urologists and radiologists gain experience with the MRI, we will find a comfort zone where we can determine when a lesion looks like it’s suspicious and definitely needs a biopsy or when we can forego a biopsy on one that doesn’t appear to be a threat. That’s a huge advantage.”
Poole hopes that this new technology also will end the controversy about whether prostate-specific antigen (PSA) screening does more harm than good in the prediction and treatment of prostate cancer. “We believe the PSA screening needs to be done, because it helps us do a better job of determining which patients need to be treated and which ones don’t, so we can’t say that PSA screening is the problem” Poole says. “We have always maintained that the screening is not the issue; it’s the treatment of the prostate cancer, so the idea of putting your head in the sand and not doing PSA screenings any more doesn’t make sense. The problem is not finding the cancer, the problem is developing better treatments for the cancer. This MRI fusion is the first step in getting better treatment for prostate cancer. It is going to help us diagnose the cancer more accurately.”
Poole adds that there has been discussion of whether it is cost effective to do the MRI fusion on all patients. “We would do the test on people who have had a negative biopsy in the past but their PSA continues to rise. At some point, we may do all prostate biopsies this way” he says. The MRI can also be used to monitor patients who have been diagnosed with a low grade cancer and have elected to do active surveillance. “We would not be treating the cancer, we would just be watching it so we could use the MRI to monitor the prostate and make sure there is nothing there that could develop into a more aggressive cancer.”
Currently, insurance companies do not cover the added cost of the MRI fusion, but Poole believes catching cancers earlier and recognizing cancers that don’t need to be treated will save money in the long run. His group will use the fusion screening regardless of the insurance coverage because it is better for their patients. “I believe this fusion technology will revolutionize the treatment of prostate cancer,” he says, “and it is a major priority for our group to offer this to patients. This is just the first step in the fight against prostate cancer. There is more to come.”